Fuel dispensers are used to dispense fuel to vehicles and other equipment requiring fuel for operation. The basic components of a fuel dispenser are as follows. The fuel dispenser includes a fuel conduit that receives fuel from a fuel source and directs the received fuel to an outlet to be dispensed into desired equipment when the fuel dispenser is activated. A pump, either self-contained within the fuel dispenser or located outside the fuel dispenser but coupled to the fuel conduit, provides the pumping force to direct the fuel through the fuel dispenser when activated. Once the fuel is pumped into the fuel conduit inside the fuel dispenser, it encounters a number of fuel-handling components located inline the fuel conduit before eventually being delivered. For example, the fuel encounters a meter to measure the amount of fuel being dispensed. A fuel flow control valve is located inline the fuel conduit either on the inlet or outlet side of the meter to control whether the fuel is allowed to pass through the fuel conduit to the outlet of the fuel dispenser. The outlet of the fuel dispenser is typically comprised of a flexible hose that is coupled to the fuel conduit on one end and to a nozzle on the other. A user engages the nozzle handle trigger to allow fuel flow. The nozzle also contains its own fuel flow control valve that is trigger-activated by the user.
An example of a fuel dispenser that is employed in the aviation industry, in particular to fuel aircraft, is illustrated in FIGS. 1A and 1B. As shown, a refueling truck 10 is provided that contains an onboard fuel tank 12 and an onboard fuel dispenser 14. The refueling truck 10 is mobile so that the onboard fuel dispenser 14 can be conveniently located proximate the desired aircraft for refueling the aircraft. Thus, the fuel tank 12 is located onboard. This is different from typical automobile fuel dispensers that are static and are not transported on trucks or other vehicles. As a result, fuel tanks 12 used to provide fuel to automobile fuel dispensers are located separate from the fuel dispenser, typically beneath the ground. Examples of typical automobile fuel dispensers are described in U.S. Pat. Nos. 5,719,781 and 6,470,233, each of which is incorporated by reference herein in its entirety. However, a typical automobile fuel dispenser contains similar components and performs similar functionalities to an aircraft refueling truck 10 with an onboard fuel dispenser 14.
As shown in the close-up illustration of the fuel dispenser 14 in FIG. 1B, a meter 16 is coupled inline the fuel conduit 18 to measure the fuel as it is delivered. A registration device or computer 20 is coupled to the meter 16 that converts the amount of fuel delivered through the meter 16 into a volumetric measurement, typically in the form of gallons. The computer 20 may also further convert the volumetric measurement into a price charged to the user for the fuel. The computer 20 typically contains a display that displays the volume of fuel dispensed, and price if applicable. After the fuel exits the meter 16 through the fuel conduit 18, the fuel is delivered to a hose 22 coupled to fuel conduit 18. The user unwinds the hose 22, which is coiled in the example of the refueling truck 10 illustrated, and places the nozzle (not shown) coupled to the end of the hose 22 to the aircraft (not shown) desired to be refueled.
Debris/particulates and undissolved water can collect inside the fuel tank 12. Debris may be present due to debris being passed into the fuel tank 12 when fuel tank 12 is filled itself. Debris may also be present by rust or other failures of the material used to construct the inside of the fuel tank 12. Water may also collect inside the fuel tank 12 as a result of condensation. Both debris and water in fuel can be hazardous to a vehicle and especially aircraft, because it may cause the engine to be disrupted and/or not perform in a safe manner. For this reason, it is important to prevent debris and water from being dispensed into a vehicle or aircraft fuel tank that will reach its engine. Manual inspection tests, water tests, and particle contaminant tests are employed to inspect fuel quality periodically by refueling personnel. For example, some fuel is dispensed into a jar or clear container called a “sight jar” that is typically mounted on the refueling truck 10 to visually inspect the fuel for impurities. Manual water tests are employed to detect the presence of water. A manual particle test may ups taps in the fuel streams and strip color to visually determine particle levels. These tests are subjective and subject to human error. Further, the test results are typically logged in a log book, thereby increasing the possibility for error due to the human factor. Log books can also be disputed. Further, these tests may only be performed after bad or unacceptable fuelings have taken place.
As a result, filters are employed as an automatic method to prevent debris and water from passing through to the aircraft. An example of a fueling filter is the Filter water separator/filter monitor filter manufactured by Facet, Velcon, or Faudias described at http://www.facetusa.com/f_aviation_index.htm, which is incorporated herein by reference in its entirety. The filter is coupled inline the fuel conduit 18. The 1583 monitor filter not only collects debris, but also contains an absorbent material that collects water present in the fuel. However, filters can clog. Filters can clog by collecting and blocking debris or water, which closes off the size of the fuel flow path internal to the filter. As a result, the pressure differential across the filter increases. If the pressure goes too high, say 15 psi for example, the filter itself may break down causing debris to be passed on in the fuel to the vehicle or aircraft. Thus, a differential pressure sensor is often further employed to measure the pressure increase across the filter to indicate that the filter is clogged or may not be working properly. An increase in pressure beyond a certain threshold is indicative of a blockage. The filter can then be manually changed with a new, unclogged filter as a result.
One example of such a filter that employs a differential pressure monitor is the differential pressure filter gauge manufactured by Gammon, described at http://www.gammontech.com/mainframe/pdf/b025.pdf, which is incorporated herein by reference in its entirety. The filter apparatus contains a steel ball that is visible to refueling personnel and which floats higher in proportion to higher pressure across the filter. If the float reaches a level that indicates too high of a differential pressure across the filter, say 14 psi for example, the refueling personnel interlocks the fuel conduit 18 and replaces the filter. Refueling personnel often attempt to continue refueling without replacing the filter, say for example when the differential pressure reads 12 psi, as a result of the refueling personnel slowing the flow rate. This decreases the pressure across the filter, thus making it less likely the filter will break down. Or, refueling personnel will prematurely replace the filter when the differential pressure is not high enough to warrant such action, thereby increasing downtime and operation costs. These filters suffer from manual inspection as well as the subjective decision making of the refueling personnel.
As a result of this manual inspection by refueling personnel, some filters further include a proximity sensor that automatically detects when the steel ball reaches the unsafe pressure level and before the filter breaks down. The proximity sensor causes the fuel dispenser 14 to shut down to disallow fueling until refueling personnel replace the filter.
While these present methods of ensuring fuel quality are acceptable for fuel to be dispensed, manual tests are required that are subject to human error, subjective decision making, non-guaranteed execution, and further may only be performed after bad refuelings have taken place. In addition, the methods either rely on refueling personnel to replace filters at the correct time, or if a system is employed to shut down the truck when the differential pressure across the filter exceeds the safe level automatically, fuel flow is ceased abruptly and without warning, thus additionally inconveniencing the refueling personnel and the aircraft expecting to be refueled. Also, refueling personnel make subjective decisions to slow flow rate based on a visual inspection of the differential pressure across the filter to lessen the likelihood of a filter break down. As a result, the fuel quality of fuel delivered may be inconsistent and throughput efficiency may be reduced by not replacing the filter in a timely and predicted manner.
It is a desire and goal of the present invention to monitor and determine fuel quality continuously, before a bad or unacceptable refueling takes place, and to not rely on the subjective decision making of refueling personnel to take corrective measures, such as when to replace a filter that collects debris and water.